“In particular, the notion that Mr Lee did not knowingly grant Pow! exclusive rights to his creative works or his identity is so preposterous that we have to wonder whether Mr Lee is personally behind this lawsuit.”

It added: “The evidence, which includes Mr Lee’s subsequent statements and conduct, is overwhelming and we look forward to presenting it in court.”

Lee is the co-creative force behind many superhero characters, including Black Panther and Spider-Man.

The lawsuit alleges Pow! chief executive Shane Duffy and co-founder Gill Champion “conspired and agreed to broker a sham deal to sell Pow! to a company in China and fraudulently steal Stan Lee’s identity, name, image, and likeness as part of a nefarious scheme to benefit financially at Lee’s expense”.

The complaint, lodged at Los Angeles County Superior Court, states Lee does not recall signing sale documents, nor having them read to him.

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Joan Lee, Stan’s wife of almost 70 years, died last July aged 95

The suit draws attention to the death of Lee’s wife last July, and his degenerative eye condition which has caused his poor eyesight, suggesting he could not have read the documents.

The legal papers also say Pow! took control of Lee’s personal social media accounts. He appeared to regain control of his Twitter account on Tuesday and used the platform to tell fans his social media channels had been “hijacked”.